M4maths Previous Puzzles

28 Feb 2013 Sequence

What is the next number of the following sequence
sqrt2, sqrt45, sqrt200, sqrt539,....

OPtion

1) Sqrt 1256
2) Sqrt 1136
3) Sqrt 1176
4) Sqrt 1134
5) Sqrt 1196
6) Sqrt 1364
7) Sqrt 1424
8) Sqrt 1481
9) Sqrt 1525
10) None of these

Solution

Sqrt 2 = 1*Sqrt 2
Sqrt 45 = Sqrt 9*5 = 3*sqrt 5
Sqrt 200 = Sqrt 25*8 = 5*Sqrt 8
Sqrt 539 = sqrt 49*11= 7*Sqrt 11
= 9*Sqrt 14 = sqrt 81*14 = Sqrt 1134
option is 4

Correct Option: 4 Best Solution (4)

27 Feb 2013 word problem

A dealer sells a toy for Rs. 24 and gains as much percent as the cost price of the toy, then cost price of the toy is...

OPtion

1) 6
2) 12
3) 16
4) 18
5) 20
6) 24
7) 28
8) 36
9) 48
10)None of these

Solution

Let the cost price of toy be Rs. x. Then
Gain x% = Rs (x*(x/100)) = Rs.. x^2/100
Now SP = CP + Gain
24 = x+(x^2/100)
Put the value and solve
then ans is in quadratic for
and is -120 and 20
price can not be negative
ans is 20
option 5

Correct Option: 5 Best Solution (26)

26 Feb 2013 speed

Two cars A and B start from the same point. 'A' travels at a constant speed of 10 km/hr but 'B' starts with 5 km/h and every hr its speed increases by 0.25 km/hr. After how many hours will B overtake A?

OPtion

1) 21 hr
2) 26 hr
3) 31.5 hr
4) 41 hr
5) 41.5 hr
6) 46 hr
7) 59.5 hr
8) 52 hr
9) 57 hr
10) None of these

Solution

Let the time taken by B to overtake A be t hours
So distance travelled by B = Distance Travelled by A (i)
distance Travelled by A in t hr = speed * time
= 10t
and Distance travelled by B =
5, 5.25, 5.50, 5.75, ........... t
Total Distance = n/2(2a+(n-1)d) (by using AP)
therefor 10t = t/2(2*5+(t-1).25) ........by (i) equation
so t = 41 (Solve)
option no 4

Correct Option: 4 Best Solution (12)

25 Feb 2013 Problem

A factory kept increasing its output by the same percentage every year. The percentage if it is known that the output is doubled in the last two years will be

OPtion

1) 34.5
2) 40
3) 41.4
4) 45
5) 49.6
6) 50
7) 49
8) 51
9) 20
10) none of these

Solution

let principle = x
and y is the multiple increment every year
so after 2 year amount = x*y*y = 2x (given)
so y^2 = 2
so y = sqrt(2)
so % = 1.414(100)-100 = 41.4

Correct Option: 3 Best Solution (22)

22 Feb 2013 height

A man standing 5 metre away from the bottom of the pole in a gravity free space throws a stone to the pole and it touches 1/3 height of the pole and makes angle of elevation 45 degree. height of the pole is..

OPtion

1) 10m
2) 15m
3) 22m
4) 25m
5) 30m
6) 34m
7) 40m
8) 45m
9) 50m
10) None of these

Solution

tan45=(1/3)h/5 (In gravity free space)
h = 15...

Correct Option: 2 Best Solution (9)

21 Feb 2013 speed

A train moving with speed 60 km/hr crosses a pole in 10 second, length of the train will be...

OPtion

1) 500/3 metre
2) 560/3 metre
3) 250/3 metre
4) 660/7 metre
5) 350 metre
6) 300 metre
7) 400 metre
8) 525 metre
9) 500 metre
10) None of these

Solution

s = d/t
60(5/10)m/s=distance/10
By solving
Distance = 500/3

Correct Option: 1 Best Solution (14)

20 Feb 2013 probability

x, y and z are 3 integers ranging 1 to 9 (repetition is not allowed). What will be the probability that x+y+z/x*y*z < 1.

OPtion

1) 1/84
2) 1/28
3) 3/28
4) 17/84
5) 43/84
6) 59/84
7) 74/84
8) 83/84
9) 1
10) none of these

Solution

Only 1*2*3 = 6 = 1+2+3
For all other triplets a*b*c > a+b+c
total no. of triplets = 9*8*7/3*2*1 = 84

Correct Option: 8 Best Solution (8)

19 Feb 2013 cube

If every side of a cube of volume V is doubled, its volume becomes kV, then the value of k is....

OPtion

1) V^3
2) k^3
3) V
4) k
5) 2k
6) 4
7) 6
8) 8
9) 8V
10) None of these

Solution

Cube Volume = side^3 (Cube has equal side)
By the given condition
let side be = a
when its doubled then side will 2a
Then V = 8a^3
but V = ka^3
8a^3 = ka^3
8=k
therefor k=8.......
option 8

Correct Option: 8 Best Solution (25)

18 Feb 2013 Number Problem

Find the next number of following sequence
1/2,2/5,3/9,5/17,7/33,.......

OPtion

1) 9/43
2) 11/43
3) 13/65
4) 11/65
5) 15/69
6) 17/73
7) 15/129
8) 11/76
9) 13/85
10) None of these

Solution

1/2 = 1/2
2/2^2+1 = 2/5
3/2^3+1 =3/9
5/2^4+1 = 5/17
7/2^5+1 = 7/33
11/2^6+1 = 11/65
option 4

Correct Option: 4 Best Solution (5)

15 Feb 2013 Find the age

A father said to his daughter that his age was 4 time her age and 8 year before his age was 10 times her age. What will be the sum of their present age

OPtion

1) 40
2) 45
3) 50
4) 53
5) 55
6) 60
7) 63
8) 65
9) 68
10) none of these

Solution

12 and 48

Correct Option: 6 Best Solution (0)